Set up ISPConfig for my domain

I just read the guide on "How To Run Your Own Name Server With ISPConfig
And providerdomain.de (Schlund)". It's just that I don't have a domain at providerdomain.de so the CP for my domain is different. Just wondering if someone could tell me what to change to make it work. I want to be able to set up own subdomains with ISPConfig on my homeserver.

I don't know your admin CP, but right now you're creating records in the admin CP AND in ISPConfig. In your admin CP, all you have to do is specify the nameservers for your domain; in ISPConfig you then create the records.